This invention relates to an assembly for sheathing or forming generally curved surfaces with polymeric or metallic materials.
Generally the term curved surfaces as used within the scope of the present invention is understood to mean surfaces of revolution, cylindrical surfaces, translation surfaces and prismatic surfaces formed by structural members.
More particularly, such generally curved surfaces can be produced or formed, on the one hand, by generally curved shell sections, such as, for example, concrete shells, thin sheets of fabric, curved deep-drawn sheet metal, pneumatic constructions, and, on the other hand, by a structure including polygonal arrangement of supporting elements, such as, for example, rods, wire ropes, cables, beams, trusses and purlins.
In the manufacture of generally curved surfaces of, for example, concrete or sheet-metal shells, the structural element or member carries the local or sectional forces, e.g. bending stresses, transverse forces, normal forces, torsional forces, etc. In addition, such structural elements, frequently in conjunction with additional sheathings or linings often serve to protect the space defined, for example, in the interior of the structure from weather and atmospheric influences.
If surfaces defining a generally three-dimensionally curved configuration are erected with the aid of a polygonal arrangement of supporting elements, a lining or sheathing is normally required which is conformed to the openings or interstices provided by this arrangement. This sheathing, in the form for example of a skin having the same shape as the openings in the frame can be arranged in all practicable planes of the polygonal joints, that is in all planes which are formed by using those polygonal joints which are necessary to mount the sheathing on.
Thus, for example, a roof arrangement with a roof skin or lining serving as the sheathing has been employed as the roof of the Olympia Stadium in Munich. In this connection, an extensively orthogonal cable network was utilized as the supporting construction or elements for the roof, The German Architect, a publication of the German Architects' Association, vol. 8/72, pp. 569-583.
A roof arrangement in which the roof skin is placed on the underside is known, for example, from the tent roof of the German Pavilion at the 1967 World's Fair in Montreal. Here again, the supporting structure is a cable network, Plastics, vol. 1/73, pp. 21-23.
Also, the pavilion of the "Aluminum Center" for the Hannover Fair, constructed as a hyperbolic paraboloid, has a sheathing covering a generally curved surface on its underside, Central Issue for Industrial Construction, vol. 5/72, pp. 178-181.
In the manufacture of a generally curved surface employing a frame of bending girders, lattice girders, rafters or purlins, for example, the network or framework produced by assembling the girders, etc. are covered, for instance, by panels of concrete, wood, synthetic resins, metal, asbestos cement, or glass. The cover panels are normally resting directly on the chords of the above-mentioned girders disposed between the nodal points or joints, which chords are especially dimensioned against intermediate bending stresses and are sufficiently rigid. In other words, the cover panels are normally resting directly on the portions of the above-mentioned girders extending between joints or points of intersection of the girders. Moreover, the girder portions extending between the joints are sufficiently rigid and especially dimensioned so as to resist bending stresses.
Finally, chords, tie rods, laths or profile members, for example, of steel, metal, wood or synthetic resin, for example, are arranged crosswise on a supporting structure or frameword, for example for the manufacture of rear-ventilated facades. The thus-produced framework or network is lined with the materials customary in the building industry by attaching thereto panels generally having the configuration of the openings in the framework by means of nails, screws, clamping means and the like.
However, as is known, covering of a generally curved surface presents difficulties if the load-bearing portion of the structure, i.e. the structural member is present, for example, in the form of a shell. Such difficulties are also encountered in structures employing a frame having a polygonal arrangement of support elements if the elements forming the mesh-like frame are not parallel to one another, as for example when they are arranged in a mutually skewed arrangement or when they enclose or define twisted and/or torsionally distorted curved areas. Such configurations are produced, for example, in a rope system by the intersecting generatrices of a hyperboloid of revolution. In this system pretensioned meridian ropes, to obtain a pretensioning and a curvature in the generatrices, can be additionally extended through the rope clamps disposed in the points of intersection of the generatrices. The openings or interstices formed by the intersecting generatrices are generally different either with respect to their dimensions which depend on the position in the rope network, or because the generatrices are not parallel to one another. Additional difficulties are encountered in this type of rope network construction, on the one hand, because no right angles are produced by the intersecting generatrices and, on the other hand, because the generatrices which lie side-by-side are askew with respect to one another and in addition have distortions caused by pretensioned meridian ropes.
For the reasons set out above, the covering of such generally curved surface areas has been possible heretofore only at great financial and technical expenditure. It is, therefore, an object of the present invention to provide improved covering or sheathing systems for producing structures having curved surfaces.
In addition, it is a further object of the present invention to provide a system by means of which generally three-dimensional surface areas can be lined or covered in a simple and economical manner.